Meat packer margins improved for the first time in several weeks last week with gains in beef and pork prices offsetting gains in market animal values. Beef packer margins improved by $17/head last week but remain at their second-lowest levels in the past 15 years due to high fed cattle costs. Pork packer margins turned positive last week after dipping into the negative the prior week with gains in the pork cutout driving the swing.  Livestock feeding profits were ...